Evaluating the geomorphic response from sand fences on dunes impacted by hurricanes

Abstract

The coastal zone is morphologically dynamic and a range of engineering practices are used to stabilize it. The dune system serves as the first line of defense against storms and rising sea levels. Sand fences on dunes are one popular and economical restorative engineering alternative. This study evaluates the geomorphic response of dunes with and without sand fences resulting from the impact of high energy events, specifically Hurricanes Florence and Michael, which impacted South Carolina, United States in 2018. Innovative cost-effective field methods were applied to calculate dune volumes on a mechanical dune. Measurements compared a site with eleven sand fences and an unmodified control site. Dune volume decreased after Hurricane Florence for the fenced and control sites and increased after Hurricane Michael for the fenced site. There was differential geomorphic change post-storm between the control and fenced sites. Results support that sand fences are resilient under high wind conditions and are an effective strategy to aid in dune recovery and growth, suggesting that they can be installed prior to the storm season rather than being reserved as a post-storm recovery technique.